<!--
Copyright 2018 Google LLC
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
    https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<!-- [START picker_html] -->
<!DOCTYPE html>
<html>
<head>
  <link rel="stylesheet" href="https://ssl.gstatic.com/docs/script/css/add-ons.css">
  <script>
    // IMPORTANT: Replace the value for DEVELOPER_KEY with the API key obtained
    // from the Google Developers Console.
    var DEVELOPER_KEY = 'ABC123 ... ';
    var DIALOG_DIMENSIONS = {width: 600, height: 425};
    var pickerApiLoaded = false;

    /**
     * Loads the Google Picker API.
     */
    function onApiLoad() {
      gapi.load('picker', {'callback': function() {
        pickerApiLoaded = true;
      }});
     }

    /**
     * Gets the user's OAuth 2.0 access token from the server-side script so that
     * it can be passed to Picker. This technique keeps Picker from needing to
     * show its own authorization dialog, but is only possible if the OAuth scope
     * that Picker needs is available in Apps Script. Otherwise, your Picker code
     * will need to declare its own OAuth scopes.
     */
    function getOAuthToken() {
      google.script.run.withSuccessHandler(createPicker)
          .withFailureHandler(showError).getOAuthToken();
    }

    /**
     * Creates a Picker that can access the user's spreadsheets. This function
     * uses advanced options to hide the Picker's left navigation panel and
     * default title bar.
     *
     * @param {string} token An OAuth 2.0 access token that lets Picker access the
     *     file type specified in the addView call.
     */
    function createPicker(token) {
      if (pickerApiLoaded && token) {
        var picker = new google.picker.PickerBuilder()
            // Instruct Picker to display only spreadsheets in Drive. For other
            // views, see https://developers.google.com/picker/docs/#otherviews
            .addView(google.picker.ViewId.SPREADSHEETS)
            // Hide the navigation panel so that Picker fills more of the dialog.
            .enableFeature(google.picker.Feature.NAV_HIDDEN)
            // Hide the title bar since an Apps Script dialog already has a title.
            .hideTitleBar()
            .setOAuthToken(token)
            .setDeveloperKey(DEVELOPER_KEY)
            .setCallback(pickerCallback)
            .setOrigin(google.script.host.origin)
            // Instruct Picker to fill the dialog, minus 2 pixels for the border.
            .setSize(DIALOG_DIMENSIONS.width - 2,
                DIALOG_DIMENSIONS.height - 2)
            .build();
        picker.setVisible(true);
      } else {
        showError('Unable to load the file picker.');
      }
    }

    /**
     * A callback function that extracts the chosen document's metadata from the
     * response object. For details on the response object, see
     * https://developers.google.com/picker/docs/result
     *
     * @param {object} data The response object.
     */
    function pickerCallback(data) {
      var action = data[google.picker.Response.ACTION];
      if (action == google.picker.Action.PICKED) {
        var doc = data[google.picker.Response.DOCUMENTS][0];
        var id = doc[google.picker.Document.ID];
        var url = doc[google.picker.Document.URL];
        var title = doc[google.picker.Document.NAME];
        document.getElementById('result').innerHTML =
            '<b>You chose:</b><br>Name: <a href="' + url + '">' + title +
            '</a><br>ID: ' + id;
      } else if (action == google.picker.Action.CANCEL) {
        document.getElementById('result').innerHTML = 'Picker canceled.';
      }
    }

    /**
     * Displays an error message within the #result element.
     *
     * @param {string} message The error message to display.
     */
    function showError(message) {
      document.getElementById('result').innerHTML = 'Error: ' + message;
    }
  </script>
</head>
<body>
  <div>
    <button onclick='getOAuthToken()'>Select a file</button>
    <p id='result'></p>
  </div>
  <script src="https://apis.google.com/js/api.js?onload=onApiLoad"></script>
</body>
</html>
<!-- [END picker_html] -->
